Public Lab Research note


HOMEMADE SPECTROMETER FOR SAMPLE ABSORPTION ANALYSIS AND A TYPE OF RAMMAN SPECTROSCOPY

by homechemist | August 30, 2013 10:09 | 817 views | 4 comments | #9077 | 817 views | 4 comments | #9077 30 Aug 10:09

Inspired by the Public Lab great ideas and by one of the techniques that my chemistry teacher used to use for lights and color experiments, I have developed a new spectrometer design that in my opinion offers much more stability and high quality and reliable results.

This is my prototype:

PROTOTIPO.jpg

So , the idea is that 20 white led bulb and two HeNe lasers of 532 nm and 655 nm emit energy in form of light, these light passes thought a Parchment paper that blurs it, Then the light passes thought the test tube that contents our sample .(At this point the molecules of the sample absorb some of the light emitted by the whites led) , then the modified light enters by a little slit in a completely dark chamber, just before impact against a dvd piece that spreads out the light in several colors according to the wavelength. The spread light travel thought the chamber and get the VGA sensor that records the spectrum and transmit it by USB to a laptop .The difference between these new spectrometer design is that is much more reliable an sure measurement than other designs because the sample , the sensor, and the light bulb keep their positions in each measurements so the spectrum which can be modify by several factors will be much more reliable as all of these factors are controlled. Another great thing of these spectrometer is that the lasers emit a well-known wavelength so the calibration is much more accurate than the fluorescent lamp one. And the calibration should be done just one a month or something like that, so, you guarantee the spectrum is well calibrated. Another real interesting thing of these spectrometer is that just between the sample and the parchment paper there is a little chamber where you can set a color filter that restrings the wavelength of the light , so the conventional spectrometer offers you the possibility of uses as a Raman spectrometer that is use for irradiating a sample with an specific wavelength that excited the molecules which electrons absorbs energy going to upper energy levels and as they return with the standard energy levels they emit an specific wavelength , that sometimes give us a fluorescent effect, these is the mode of analysis of the Raman spectrometer.

I HAVE TO RECOGNIZE THAT THE RAMAN SPECTROSCOPY IS JUST A FUTURE PROJECT AND I HAVE TO TEST IT, HOWEVER FOR DETERMINE THE CONCENTRATION OF A SAMPLE THE FILTERS WILL BE GREAT AS YOU CHOOSE THE WAVELEGHNT THAT YOUR SAMPLE ABSORBS

Here I show you the laser calibration LASERS.jpg

High concentrated chlorophyll spectrum diluited in non polar solvent (extracted from spinach)

CLOROFILE.jpg

And now what?..Okay so , at the moment I am trying to get soil and oil samples to contribute to the open database and, as I have access to a lot of chemicals I will upload a lots of spectrums ,and I hope in a few time The great people that works In Public Lab will be able to create a fingerprint app for the analysis software that allow us to determine what chemical do we have in our sample.

As a future project I promise I will continue investigating in this prototype of Raman Spectrometer and in the determination of the concentration of a sample with wavelength filters. I am also interesting in the isolation of photosynthetic and natural pigments which have a lot of interesting behaviors and proprieties

If you want to get in touch with my please do it :) at this mail: miguelgallegosgonzalez@gmail.com

And if you want to see more of my recent work you can enter in the database and search "homechemist" the spectrum toke by this spectrometer are the ones that sais: calibration cloned from lasers

Finally I am really interesting in capturing the spectrum of colorful changing chemical reaction like the Ph. ones so you can determine how the protonation and the DE protonation affects at the indicators molecules( the simplest indicator is the Lombard which contents anthocyanin , a natural Ph. indicator)

The spectometer:

DSC_2842.jpg

The chlorophyll:

cl.jpg

Miguel Gallegos


4 Comments

Hi, Miguel - excellent and exciting to see your work!

What kind of non polar solvent did you use? That's like, some kind of oily substance?

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Thank you very much , at first I have to said that this project wouldn’t be possible without your collaboration (Public Lab)

And yes , at first you triturate and mix spinach with ethanol so the carotenoids and the chlorophylls leave the cells to get the ethanol solution(polar solvent) then you add a noonpolar solvent which means that the molecule is electrically uniform , so the chlorophyll leave the polar solution to get the noonpolar one, and now you have isolate the carotenoids in the polar phase and the chlorophylls in the non-polar one(Remember that non-polar and polar solvents never mix , they keep separate form each other)

The non-polar solvent that I used is petroleum ether a highly oily substance that smells a lot and is hard to clean from glassware...but you can also use toluene,xilene,ethyl acetate, chloroform and some others If you are interesting in the technique of isolation or you want me to extract the chlorophylls in other solvent please just send me a message

Petroleum ether is basically refined petroleum and it contents a lot of hydrocarbons

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Wow... where do you get petroleum ether? I'm very interested in the isolation technique... is it applicable to other sample preparation, like for detecting petroleum or metals in soil?

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Well , petroleum ether is a very common chemical is it use for dissolving paintings and for cleaning painting brushes, I am thinking that is possible that if you are trying to found petroleum in soil and you use water to extract the chemicals from the soil the petroleum won´t leave the soil as the water is a POLAR solvent and I suppose that petroleum is a nonpolar substance so it´s only soluble in nonpolar solvents, so lets try with a non polar solvent I think you might get better results but I promise I will study that...and the metals you are looking for is difficult to Know but if the are salts, I suppose so( iron oxide, some metal sulfates...and some others) they are soluble in Polar solvents as the water.

If you are interested in the isolation technique please told me details of the sample you want to extract from and i will do it in my home lab and I will send you the results , If I have access to it .

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